1. Field of the Invention
The present invention relates to a printed circuit board, and more particularly, to a printed circuit board that provides a variable inductance.
2. Description of the Related Art
Owing to the recent development in the integrated circuit (IC) process technology, it is possible to manufacture radio frequency ICs (RFIC) for a plurality of applications such as wireless communication, networking, and computing. In recent times, with the adoption of multi-band/multi-mode, various systems such as cellular communication, WiFi communication, and Bluetooth communication are implemented as one-chip.
This RFIC may include various analog circuit blocks which are previously implemented as large individual circuit components. The analog circuit blocks use reactance components such as a capacitor and an inductor to achieve designed functions. For example, a filter, a resonator tank, and an impedance matching network, etc. may include a capacitor and an inductor to obtain a desired circuit response.
In this circuit, in order to provide the possibility of some degree of tuning, it is known that variable capacitor and inductor, that is, a capacitor and an inductor in which a value can vary to a specific range are used. A very well-know example of this variable element is a so-called varicap diode that allows a specific change in capacitance value by applying a continuous variable voltage.
However, an example of the variable inductor is not almost known. Even in case of an of an inductor 1 shown in FIG. 1, the inductor, which increases an inductance value by connecting lines 10 of respective layers through a via 20, is used, but the above inductor 1 fixedly uses the required inductance value.
However, the variable inductor is very useful for the above circuit etc. For example, it is possible to provide a variable inductance to integrated circuits etc. capable of various applications in wireless communication systems, thus enabling tuning according to output characteristics of each IC. Further, when the output characteristics of the IC are changed because of reasons such as variations in manufacturing processes, if it can be tuned to an inductance value corresponding to the output characteristics of the IC, it is apparent that it is very efficient in securing mass-productivity etc.
However, inductors 2 shown in FIG. 2 are implemented in an IC, resulting in an increase in size of the IC. Accordingly, it becomes a burden in terms of miniaturization and cost.
Therefore, above all, it is needed to develop a variable inductor that can achieve miniaturization and cost reduction as well as tune output characteristics of each IC and respond sensitively to changes in characteristics according to manufacturing processes in integrated circuits etc. capable of various applications.